1. Technical Field
This application relates a non-chemical, mechanical procedure for the devulcanization of scrap rubber and/or elastomers and apparatus therefor.
2. Background Information
Background information is for informational purposes only and does not necessarily admit that subsequently mentioned information and publications are prior art. Rubber consists of or comprises natural rubber and/or artificially produced elastomers the molecules of which have experienced a crosslinking. Amongst other, sulphur-carbon compound and sulphur-sulphur compounds between the molecules are known. Thereby it is also referred to as cross linkings.
Due to the crosslinking the characteristics of the material are changed drastically. This refers especially to the strength, elasticity and the thermal carrying capacity.
Rubber is mostly applied in the automotive industry. The carrying capacity of car tires is legendary.
Depending on the run kilometers of the tires there is a wear condition which is matched with the wear of the profile of the tires. When the profile falls below a certain thickness a tire change must be carried out.
Old tires and scrap rubber respectively occur.
In fact, there are different proposals existing for the chemical treatment of scrap rubber, the expenditure, however, is so high, that nearly no use is made of them. Scrap rubber may be fed to combustion. Thereby the cement industry has proved to be a big consumer. There, scrap rubber as well is burned in the rotary furnaces. The cement rotary furnaces have a long combustion line so that unburned gases will be combusted. Thus, an environmental pollution is excluded.
The cement industry, however, mostly asks for a contribution for the combustion of the scrap tires.
Moreover, the disposal of scrap tires is no longer treated as contemporary.
Therefore, efforts are made since long concerning the recycling of rubber and elastomers.
Thereby different ways are followed.
As per DE60004885T2 modifying agents are used for the devulcanization of hardened (crosslinked) elastomers and rubber. These modifying agents consist totally or partly of adipic acid or oxalic acid. Moreover additives are used which consist of sulphur, zinc oxide and stearic acid.
In DE 909041 edeleanu extracts, which are generated from the crude oil processing, are scheduled as modifying agents. Thereby, e.g. kerosene, nitrobenzene, furfurol, phenol, dichlordiethylene ether are concerned.
The DE 60008279T2 provides amine compounds as devulcanization agent/modifying agent.
DE60215210T2 provides aromatic oil, naphthenic oil or paraffinic oil as devulcanization agent.
Der60306089T2 provides 2-butanol and carbon dioxide as devulcanization agent.
Also DE60120804T2 provides modifying agents. However, the oil is generated out of the recyclate itself.
From the application's view the modifying agents have the disadvantage that the modifying agents remain totally or partly in the recyclate and that they restrict the usability of the recyclate very much.
Also a devulcanization without chemical agents is known.
Possibly utilized or adapted for use in this application are microwaves and ultrasonic waves. With the waves a strong mechanical stress of the rubber and the elastomers is generated with which the molecular chain shall be broken open. The mechanical stress can be completed by using heat and high vapour pressure respectively.
Nevertheless, this kind of devulcanization is judged as insufficient, cp. for example DE60120804T2.
Also the application pursues the task to recycle the scrap rubber economically.
Thereby, the embodiments illustrate another way to pursue this goal.